191,921 Works

Characterization of Impact Toughness Properties of DIN39MnCrB6-2 Steel Grade

João Paulo Gomes Antunes & Carlos Angelo Nunes
Boron added steels in quenched and tempered condition have been widely used in applications where good mechanical properties and low cost are required. In this study, impact resistance of DIN 39MnCrB6-2 steel grade was investigated due to its criticality in automotive components. Metastable phase diagrams were built to guide heat treatments. The influence heat treatment parameters and initial microstructure were evaluated. Impact toughness results showed low absorbed energy (<30J) for all tempering temperatures. CVN impact...

Characterization of Impact Toughness Properties of DIN39MnCrB6-2 Steel Grade

João Paulo Gomes Antunes & Carlos Angelo Nunes
Boron added steels in quenched and tempered condition have been widely used in applications where good mechanical properties and low cost are required. In this study, impact resistance of DIN 39MnCrB6-2 steel grade was investigated due to its criticality in automotive components. Metastable phase diagrams were built to guide heat treatments. The influence heat treatment parameters and initial microstructure were evaluated. Impact toughness results showed low absorbed energy (<30J) for all tempering temperatures. CVN impact...

Effect of PANI on Thermal, Mechanical and Electromagnetic Properties of HDPE/LLDPE/PANI Composites

Patrick Valadão De Faria, Eduardo Henrique Backes, Larissa Stieven Montagna, Simone De Souza Pinto, Luiz Antonio Pessan, Mirabel Cerqueira Rezende & Fabio Roberto Passador
In this work, polyaniline (PANI) in emeraldine-base form, synthesized by chemical oxidation polymerization, was protonated with hydrochloric acid (HCl). Composites based on high-density polyethylene (HDPE) and linear-low density polyethylene (LLDPE) blends with PANI were prepared in molten condition using a torque rheometer. The effect of compatibilizer agent (maleic anhydride-grafted high density polyethylene, HDPE-g-MA) and different contents of PANI on the blends-based composites was also investigated. Thermal, mechanical, and electromagnetic (electric permittivity) measurements and morphological aspects...

Effect of PANI on Thermal, Mechanical and Electromagnetic Properties of HDPE/LLDPE/PANI Composites

Patrick Valadão De Faria, Eduardo Henrique Backes, Larissa Stieven Montagna, Simone De Souza Pinto, Luiz Antonio Pessan, Mirabel Cerqueira Rezende & Fabio Roberto Passador
In this work, polyaniline (PANI) in emeraldine-base form, synthesized by chemical oxidation polymerization, was protonated with hydrochloric acid (HCl). Composites based on high-density polyethylene (HDPE) and linear-low density polyethylene (LLDPE) blends with PANI were prepared in molten condition using a torque rheometer. The effect of compatibilizer agent (maleic anhydride-grafted high density polyethylene, HDPE-g-MA) and different contents of PANI on the blends-based composites was also investigated. Thermal, mechanical, and electromagnetic (electric permittivity) measurements and morphological aspects...

Synthesis and Characterization of Non-Linear Optical Crystal of Manganese Mercury Thiocyanate Glycol Monomethyl Ether

Cynthia Sundararaj & Suresh Sagadevan
The design and synthesis of organic nonlinear optical (NLO) crystals are a promising area of current research in materials science. Organic materials are found to possess better non linear optical properties when compared to inorganic materials. Recently, there has been a widespread interest in the metal-organic coordination compounds, which are a combination of metal and organic ligands, having exciting NLO properties. Non-linear optical single crystals of Manganese mercury thiocyanate glycol monomethyl ether (MMTG) were grown...

Synthesis and Characterization of Non-Linear Optical Crystal of Manganese Mercury Thiocyanate Glycol Monomethyl Ether

Cynthia Sundararaj & Suresh Sagadevan
The design and synthesis of organic nonlinear optical (NLO) crystals are a promising area of current research in materials science. Organic materials are found to possess better non linear optical properties when compared to inorganic materials. Recently, there has been a widespread interest in the metal-organic coordination compounds, which are a combination of metal and organic ligands, having exciting NLO properties. Non-linear optical single crystals of Manganese mercury thiocyanate glycol monomethyl ether (MMTG) were grown...

B-N Codoped p Type ZnO Thin Films for Optoelectronic Applications

Nripasree Narayanan & Nangarath Kannoth Deepak
The success of codoping by donor-acceptor impurities in accomplishing p type ZnO thin films deposited by spray pyrolysis technique is reported here. Monodoping ZnO with N altered the conductivity type but the resistivity is too high making it practically impossible to be useful in optoelectronic applications. B-N codoping increased the carrier concentration and obtained comparatively low resistivity because codoping enhanced the acceptor incorporation by forming acceptor-donor-acceptor complex in the band gap. XRD analysis revealed the...

B-N Codoped p Type ZnO Thin Films for Optoelectronic Applications

Nripasree Narayanan & Nangarath Kannoth Deepak
The success of codoping by donor-acceptor impurities in accomplishing p type ZnO thin films deposited by spray pyrolysis technique is reported here. Monodoping ZnO with N altered the conductivity type but the resistivity is too high making it practically impossible to be useful in optoelectronic applications. B-N codoping increased the carrier concentration and obtained comparatively low resistivity because codoping enhanced the acceptor incorporation by forming acceptor-donor-acceptor complex in the band gap. XRD analysis revealed the...

Study and Assessment of the Efficiency of the Cocoa Bark Extracted from the Theobroma Cacao as an Inhibitor of the Corrosion of Carbon Steel in Substitution of Benzotriazole

Lhaira Souza Barreto, Miriam Sanae Tokumoto, Isabel Correia Guedes, Hercílio Gomes De Melo, Franco Amado & Vera Rosa Capelossi
Corrosion represents high losses to the economy, therefore, researches on the minimization of its damages in materials, mainly the metallic ones, are necessary. Among the various alternatives of protection against corrosion, there is the application of corrosion inhibitors that can minimize or even stop the corrosive process of metallic materials. However, at present, substances usually used as corrosion inhibitors present high toxicity, being considered harmful components to the environment and to human health. Therefore, there...

Study and Assessment of the Efficiency of the Cocoa Bark Extracted from the Theobroma Cacao as an Inhibitor of the Corrosion of Carbon Steel in Substitution of Benzotriazole

Lhaira Souza Barreto, Miriam Sanae Tokumoto, Isabel Correia Guedes, Hercílio Gomes De Melo, Franco Amado & Vera Rosa Capelossi
Corrosion represents high losses to the economy, therefore, researches on the minimization of its damages in materials, mainly the metallic ones, are necessary. Among the various alternatives of protection against corrosion, there is the application of corrosion inhibitors that can minimize or even stop the corrosive process of metallic materials. However, at present, substances usually used as corrosion inhibitors present high toxicity, being considered harmful components to the environment and to human health. Therefore, there...

MgO Saturation Analisys of CaO-SiO2-FeO-MgO-Al2O3 Slag System

Rodolfo Arnaldo Montecinos De Almeida, Deisi Vieira, Wagner Viana Bielefeldt & Antônio Cezar Faria Vilela
Electric arc furnace (EAF) slag has a range of functions, including improving energy efficiency through the "slag foaming" phenomenon. As such, the study of slag is important in EAFs. One of the factors that determine foaming quality and efficiency is the presence of solid particles. MgO saturation is highly significant since, in addition to ensuring the presence of solid particles, it also ensures chemical compatibility to minimize refractory consumption. The present study aims to examine...

MgO Saturation Analisys of CaO-SiO2-FeO-MgO-Al2O3 Slag System

Rodolfo Arnaldo Montecinos De Almeida, Deisi Vieira, Wagner Viana Bielefeldt & Antônio Cezar Faria Vilela
Electric arc furnace (EAF) slag has a range of functions, including improving energy efficiency through the "slag foaming" phenomenon. As such, the study of slag is important in EAFs. One of the factors that determine foaming quality and efficiency is the presence of solid particles. MgO saturation is highly significant since, in addition to ensuring the presence of solid particles, it also ensures chemical compatibility to minimize refractory consumption. The present study aims to examine...

Microstructural Evolution and Phase Transformation in Laser Cladding of Cr and Mo Powder on Grey Cast Iron: Mixture Design of Experiment (DOE)

Abd Rahman Zulhishamuddin, Reza Mohamed Suffian, Syarifah Nur Aqida & Maarof Mohd Rashidi
Laser cladding on grey cast iron at high power processing was investigated for microstructural evolution and phase transformation to enhance surface properties. Cladding was designed using a mixture of DOE with peak power (Pp) and pulse repetition frequency (PRF), and a mixture component of Cr and Mo ratio as factors. Microstructural findings indicated absolute elimination of graphite phase from the clad zone, in conjunction with particles evolution occurrence. Meanwhile, Cr, Mo and Fe phases were...

Effect of Boride Incubation Time During the Formation of Fe2B Phase

Bendaoud Mebarek, Abdelbasset Benguelloula & Abdelouahab Zanoun
Our present study focuses on the numerical simulation of the boronized layer growth kinetics on the iron substrate of the XC38 steel, the boronizing treatment is performed in a liquid medium composed of borax and silicon carbide. We mainly calculated the incubation time of the boronized layer formation. Aimed at estimating the boronizing treatment kinetics of XC38 steel, we initially used experimental data. The study was conducted to determine the law of borided layers growth...

Effect of Boride Incubation Time During the Formation of Fe2B Phase

Bendaoud Mebarek, Abdelbasset Benguelloula & Abdelouahab Zanoun
Our present study focuses on the numerical simulation of the boronized layer growth kinetics on the iron substrate of the XC38 steel, the boronizing treatment is performed in a liquid medium composed of borax and silicon carbide. We mainly calculated the incubation time of the boronized layer formation. Aimed at estimating the boronizing treatment kinetics of XC38 steel, we initially used experimental data. The study was conducted to determine the law of borided layers growth...

Microstructural Evolution and Phase Transformation in Laser Cladding of Cr and Mo Powder on Grey Cast Iron: Mixture Design of Experiment (DOE)

Abd Rahman Zulhishamuddin, Reza Mohamed Suffian, Syarifah Nur Aqida & Maarof Mohd Rashidi
Laser cladding on grey cast iron at high power processing was investigated for microstructural evolution and phase transformation to enhance surface properties. Cladding was designed using a mixture of DOE with peak power (Pp) and pulse repetition frequency (PRF), and a mixture component of Cr and Mo ratio as factors. Microstructural findings indicated absolute elimination of graphite phase from the clad zone, in conjunction with particles evolution occurrence. Meanwhile, Cr, Mo and Fe phases were...

Rescue Therapy with Nifurtimox and Dipyridamole for Severe Acute Chagas Myocarditis with Congestive Heart Failure in NMRI Albino Mice

Daniela Yustiz Aparicio, María González-Hernández, Greybis Hernández-Forero, María Guédez-Ortiz, Sonia Santeliz, Loredana Goncalves & Rafael Bonfante Cabarcas
Abstract Background: Chagas disease is a global health problem; therefore, the development of new therapeutic protocols is necessary. Our group recently demonstrated that nifurtimox associated with dipyridamole has curative effects in mice with acute Chagas disease. In this study, we assess the effect of this therapeutic protocol in chagasic mice with heart failure. Objective: To evaluate whether nifurtimox and dipyridamole are useful to rescue mice with severe acute chagasic myocarditis with heart failure. Methods: 42...

Rescue Therapy with Nifurtimox and Dipyridamole for Severe Acute Chagas Myocarditis with Congestive Heart Failure in NMRI Albino Mice

Daniela Yustiz Aparicio, María González-Hernández, Greybis Hernández-Forero, María Guédez-Ortiz, Sonia Santeliz, Loredana Goncalves & Rafael Bonfante Cabarcas
Abstract Background: Chagas disease is a global health problem; therefore, the development of new therapeutic protocols is necessary. Our group recently demonstrated that nifurtimox associated with dipyridamole has curative effects in mice with acute Chagas disease. In this study, we assess the effect of this therapeutic protocol in chagasic mice with heart failure. Objective: To evaluate whether nifurtimox and dipyridamole are useful to rescue mice with severe acute chagasic myocarditis with heart failure. Methods: 42...

Assessment of Right Ventricle Function and Myocardial Fibrosis by Cardiovascular Magnetic Resonance in Patients with Inferior Wall Myocardial Infarction

Priscila Neri Lacerda, Rafael Fernandes Almeida, Fernanda Gabriella Figueiredo Pinto, Adilson Machado Gomes Júnior, Jéssica Mendes Santos, Cristiano Ricardo Bastos De Macêdo, André Maurício Souza Fernandes & Roque Aras Júnior
Abstract Background: Right ventricular dysfunction (RVD) can be found in 30-50% of patients with inferior wall myocardial infarction (I-MI) and predicts early mortality. Myocardial fibrosis is associated with progressive ventricular dysfunction and severe prognosis. In these patients, cardiovascular magnetic resonance (CMR) is an important risk stratification method. Objectives: This study sought to evaluate the association between RVD and myocardial fibrosis in patients with I-MI, using CMR. Methods: Cohort study conducted in a prominent center of...

Assessment of Right Ventricle Function and Myocardial Fibrosis by Cardiovascular Magnetic Resonance in Patients with Inferior Wall Myocardial Infarction

Priscila Neri Lacerda, Rafael Fernandes Almeida, Fernanda Gabriella Figueiredo Pinto, Adilson Machado Gomes Júnior, Jéssica Mendes Santos, Cristiano Ricardo Bastos De Macêdo, André Maurício Souza Fernandes & Roque Aras Júnior
Abstract Background: Right ventricular dysfunction (RVD) can be found in 30-50% of patients with inferior wall myocardial infarction (I-MI) and predicts early mortality. Myocardial fibrosis is associated with progressive ventricular dysfunction and severe prognosis. In these patients, cardiovascular magnetic resonance (CMR) is an important risk stratification method. Objectives: This study sought to evaluate the association between RVD and myocardial fibrosis in patients with I-MI, using CMR. Methods: Cohort study conducted in a prominent center of...

Exercise Improves Cardiovascular Risk Factors, Fitness, and Quality Of Life in Hiv+ Children and Adolescents: Pilot Study

Luiz Rodrigo Augustemak De Lima, Isabela De Carlos Back, Carmem Cristina Beck & Bruno Caramelli
Abstract Children and adolescents infected by HIV through mother-to-child transmission are at high risk of developing premature cardiovascular diseases due to dyslipidemia, insulin resistance and low-grade chronic inflammation. The aim of the pilot study was to verify the effect of a playful exercise program on cardiovascular, morphological, metabolic, fitness, and quality of life outcomes. A non-randomized clinical trial consisting of 24 sessions of playful aerobic and resistive exercises was applied to 10 children and adolescents...

Exercise Improves Cardiovascular Risk Factors, Fitness, and Quality Of Life in Hiv+ Children and Adolescents: Pilot Study

Luiz Rodrigo Augustemak De Lima, Isabela De Carlos Back, Carmem Cristina Beck & Bruno Caramelli
Abstract Children and adolescents infected by HIV through mother-to-child transmission are at high risk of developing premature cardiovascular diseases due to dyslipidemia, insulin resistance and low-grade chronic inflammation. The aim of the pilot study was to verify the effect of a playful exercise program on cardiovascular, morphological, metabolic, fitness, and quality of life outcomes. A non-randomized clinical trial consisting of 24 sessions of playful aerobic and resistive exercises was applied to 10 children and adolescents...

Preparation of Au/TiO2 Catalyst by a Liquid-Phase Reduction Method for Preferential Oxidation of Carbon Monoxide in a Hydrogen Rich-Stream (CO-PROX reaction)

Julian M. De Souza Pereira, Ligia Ciotti, Jorge Moreira Vaz & Estevam Vitorio Spinacé
Au nanoparticles supported on TiO2 were prepared by a liquid-phase reduction method using HAuCl4.3H2O as the Au precursor, TiO2 as the support, a solution of ethylene glycol/water as solvent and reducing agent and sodium citrate as reducing agent and stabilizer. The Au/TiO2 catalysts were prepared using different routes and characterized by Energy-dispersive X-ray spectroscopy, X-ray diffraction and Transmission Electron Microscopy and tested for preferential oxidation of carbon monoxide in hydrogen-rich stream (CO-PROX reaction). The way...

Preparation of Au/TiO2 Catalyst by a Liquid-Phase Reduction Method for Preferential Oxidation of Carbon Monoxide in a Hydrogen Rich-Stream (CO-PROX reaction)

Julian M. De Souza Pereira, Ligia Ciotti, Jorge Moreira Vaz & Estevam Vitorio Spinacé
Au nanoparticles supported on TiO2 were prepared by a liquid-phase reduction method using HAuCl4.3H2O as the Au precursor, TiO2 as the support, a solution of ethylene glycol/water as solvent and reducing agent and sodium citrate as reducing agent and stabilizer. The Au/TiO2 catalysts were prepared using different routes and characterized by Energy-dispersive X-ray spectroscopy, X-ray diffraction and Transmission Electron Microscopy and tested for preferential oxidation of carbon monoxide in hydrogen-rich stream (CO-PROX reaction). The way...

Evaluation of the Influence of Surface Finishing on the Corrosion Resistance of HVOF Applied Inconel 625 Coatings on Steel

Mariana Sgambaro De Lorenzi, Rafael Menezes Nunes, Tiago Falcade & Thomas Clarke
In this work, the corrosion resistance of Inconel 625 coatings applied to AISI 4140 steel plates was evaluated. Coatings were produced by High Velocity Oxygen Fuel (HVOF) by use of two different equipment which use either kerosene (liquid) or propane (gas) as fuel. The resulting coatings were evaluated in two conditions: as-deposited and after a surface finishing process by grinding. Residual stress distributions in the coatings were characterized by X-ray diffraction and their morphology was...

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